Drive chain came off. lost tension idler spring. how to reassemble

The reason for this will be that you have mis-routed the belt or that the spring on the idler arm is weak or has broken / dropped off. The idler pulley puts tension on the back edge of the belt. What made the loud noise will be the key to this. My bet is that you lost the spring or an idler arm mounting bolt.

double posted but this time the CAM pops up.
why not read the FSM first. ? linked below.
or alldata.com . log in and read.

here ill do a paste from JUST install PART chapter.
you are doing ALL THAT book free, REALLY?
https://www.techauthority.com/en-US/Pages/Home.aspx

1. Using a vise, lightly compress the secondary chain tensioner piston until the piston step is flush with the tensioner body. Using a pin or suitable tool, release ratchet pawl by pulling pawl back against spring force through access hole on side of tensioner.
2. While continuing to hold pawl back, Push ratchet device to approximately 2 mm from the tensioner body. Install Special Tool 8514 lock pin into hole on front of tensioner. Slowly open vise to transfer piston spring force to lock pin.
3. Position primary chain tensioner over oil pump and insert bolts into lower two holes on tensioner bracket. Tighten bolts to 250 inch lbs. (28 Nm).
4. Install right side chain tensioner arm. Install Torx®bolt. Tighten Torx®bolt to 250 inch lbs. (28 Nm). CAUTION The silver bolts retain the guides to the cylinder heads and the black bolts retain the guides to the engine block.
5. Install the left side chain guide. Tighten the bolts to 250 inch lbs. (28 Nm).
6. Install left side chain tensioner arm, and Torx®bolt. Tighten Torx®bolt to 250 inch lbs. (28 Nm).
7. Install the right side chain guide. Tighten the bolts to 250 inch lbs. (28 Nm).
8. Install both secondary chains onto the idler sprocket. Align two plated links on the secondary chains to be visible through the two lower openings on the idler sprocket (4 o'clock and 8 o'clock). Once the secondary timing chains are installed, position special tool 8429 to hold chains in place for installation.
9. Align primary chain double plated links with the timing mark at 12 o'clock on the idler sprocket.
10. Align the primary chain single plated link with the timing mark at 6 o'clock on the crankshaft sprocket.
11. Lubricate idler shaft and bushings with clean engine oil. NOTE The idler sprocket must be timed to the counterbalance shaft drive gear before the idler sprocket is fully seated.
12. Install all chains, crankshaft sprocket, and idler sprocket as an assembly . After guiding both secondary chains through the block and cylinder head openings, affix chains with a elastic strap or equivalent. This will maintain tension on chains to aid in installation. Align the timing mark on the idler sprocket gear to the timing mark on the counterbalance shaft drive gear, then seat idler sprocket fully . Before installing idler sprocket bolt, lubricate washer with oil, and tighten idler sprocket assembly retaining bolt to 25 ft. lbs. (34 Nm). NOTE It will be necessary to slightly rotate camshafts for sprocket installation.
13. Align left camshaft sprocket "L" dot to plated link on chain.
14. Align right camshaft sprocket "R" dot to plated link on chain. CAUTION Remove excess oil from the camshaft sprocket bolt. Failure to do so can result in over torque of bolt resulting in bolt failure.
15. Remove Special Tool 8429, then attach both sprockets to camshafts. Remove excess oil from bolts, then Install sprocket bolts, but do not tighten at this time.
16. Verify that all plated links are aligned with the marks on all sprockets and the "V6" marks on camshaft sprockets are at the 12 o'clock position. CAUTION Ensure the plate between the left secondary chain tensioner and block is correctly installed.
17. Install both secondary chain tensioners. Tighten bolts to 250 inch lbs. (28 Nm). NOTE Left and right secondary chain tensioners are not common.
18. Remove all locking pins from tensioners. CAUTION After pulling locking pins out of each tensioner, DO NOT manually extend the tensioner(s) ratchet. Doing so will over tension the chains, resulting in noise and/or high timing chain loads.
19. Using Special Tool 6958, Spanner with Adaptor Pins 8346, tighten left and right . camshaft sprocket bolts to 90 ft. lbs. (122 Nm).
20. Rotate engine two full revolutions. Verify timing marks are at the follow locations: ² primary chain idler sprocket dot is at 12 o'clock ² primary chain crankshaft sprocket dot is at 6 o'clock ² secondary chain camshaft sprockets "V6" marks are at 12 o'clock ² counter balancer shaft drive gear dot is aligned to the idler sprocket gear dot.
21. Lubricate all three chains with engine oil.
22. After installing all chains, it is recommended that the idler gear end play be checked. The end play must be within mm 0.004-0.010 inches (0.10-0.25). If not within specification, the idler gear must be replaced.
23. Install timing chain cover and crankshaft damper.
24. Install cylinder head covers. NOTE Before installing threaded plug in right cylinder head, the plug must be coated with sealant to prevent leaks.
25. Coat the large threaded access plug with Mopar® Thread Sealant with Teflon, then install into the right cylinder head and tighten to 60 ft. lbs. (81 Nm).
26. Install the oil fill housing.
27. Install access plug in left cylinder head.
28. Install power steering pump.
29. Fill cooling system.
30. Connect negative cable to battery.

Hello, W/D here.

The motor drives a belt, and the belt drives a pulley that causes a chain to drive the tines (blades). For the belt to drive the tines, an idler pulley has to put tension on the belt. This is moved into position by a lever that pulls the pulley into tension on the belt, and tension is maintained with a spring when the lever is locked into place.
1. Make sure that the tines will rotate with the belt off. If there is difficulty, check for debris holding the tines (roots, etc.). If necessary, remove the cap covering the chain cover inspection port, and with the machine tilted back, observe for proper operation of the chain while moving the tines by hand. Lubricate the chain according to your manual. If your chain is not working properly, disassemble down to the chain case, and inspect the chain and sprockets. Chain is radily at places like Motion Industries, WW Grangier, or a bicycle shop. Often overlooked, check that the pulley set screws are tight, and causing the shaft attached to it to actually rotate. Check the pins and locking cotter pins in the tines, make sure that they are pinned to the shaft.
2. Check the belt. An old belt can stretch to the point where it will no longer work. The "V" belt can also wear down to where insufficient friction can be applied to the driving or the driven pulleys to cause it to rotate.
3. Check the condition of the idler pulley and spring. Make sure that the lever places tension on the belt. It should be somewhat difficult to engage the idler pulley when the belt is new. You may have an adjustor on the idler that will tighten the belt.
Best regards, --W/D-- Please provide feedback for our solutions so that we may continue to improve in helping others. Thanks.

Removal & Installation

1. Rotate the drive belt tensioner clockwise and remove the drive belt.
   WARNING Never suddenly let go of the tensioned idler pulley. The force of the spring pressure suddenly released may damage the idler pulley mechanism. Always release the spring pressure gradually.
   
   
   

   Fig. Rotate the belt tensioner to relieve tension on the belt-4.6L engine shown, others similar
   

To install:

1. Route the belt over the pulleys making sure all the grooves in the pulleys and the belt line up correctly. Refer to the accessory belt routing section of this manual.
2. Rotate belt tensioner clockwise and slip drive belt over idler pulley on tensioner.

1. Rotate the drive belt tensioner clockwise and remove the drive belt.
   WARNING Never suddenly let go of the tensioned idler pulley. The force of the spring pressure suddenly released may damage the idler pulley mechanism. Always release the spring pressure gradually.
   
   
   

   Fig. Rotate the belt tensioner to relieve tension on the belt-4.6L engine shown, others similar
   

To install:

1. Route the belt over the pulleys making sure all the grooves in the pulleys and the belt line up correctly. Refer to the accessory belt routing diagrams above.
2. Rotate belt tensioner clockwise and slip drive belt over idler pulley on tensioner.

If for any reason, the tensioner is crooked, replace it!!! Also, install the belt with the writing facing you like you are trying to read a book. This WILL (a trick I learned at Mercedes) prevent even a new belt from squeeling!!

When the cord breaks, the internal spring will completely unwind. You have to re-tension the spring, then attach the cord and wind it onto the spool while holding the spool against tension. Finally, feed the end of the cord out through the cord port and tie the handle while still holding tension. A small pair of Vise Grip pliers will hold the cord while dealing with the handle. It's about like setting a trap without getting your fingers caught. Hope this helps!

You have a self adjusting cam chain tensioner. It is sold as an assembly. Take out the complete unit and replace it with a new one. The springs are not bad , the device that keeps the pressure on the tensioner is slipping causing a ticking sound.

- remove deck
- remove seat and rear fenders
- pry off deck adjusting knob
- remove F/R pedals
- remove floor plate
- use jackstands to prop up entire right side of tractor
- remove (2) screws holding fuel lines on side of frame
- lift out gas tank, set alongside left side of tractor
- remove plastic fan from hydrostat
- disconnect the electrical connector for the electric clutch
- from the top-side - use a 3/8" drive rachet - stick it into the tensioner slot next to the idler, rotate it to take tension off the belt, and remove belt off hydrostat pulley
- from underside - remove front idler (next to electric clutch)
- from underside - remove the "right-most" idler off the spring tensioner
- from underside - remove the "left-most" idler off the spring tensioner
- now the tensioner can rotate fully to take almost all the tension off the extension spring
- pop the spring off the tensioner arm
- the belt should now be able to be removed from the machine

- reinstall in the opposite fashion
- note: to reattach the spring, connect a nylon cord to the spring, and pull it rearward and guide it onto the tensioner arm - you need to stretch it about 1"
- for reattaching the two idler pulleys to the tensioner, get someone to hold the ratchet so the tensioner is positioned for the belt being in it's most-loose position. You may need to wrap the new belt around the hydrostat pulley first, and assemble the last idler pulley and belt at the same time to complete the procedure.

Removal & Installation

1. Rotate the drive belt tensioner clockwise and remove the drive belt.
   
   WARNING Never suddenly let go of the tensioned idler pulley. The force of the spring pressure suddenly released may damage the idler pulley mechanism. Always release the spring pressure gradually.
   

Rotate the belt tensioner to relieve tension on the belt—4.6L engine shown, others similar

To install:

1. Route the belt over the pulleys making sure all the grooves in the pulleys and the belt line up correctly. Refer to the accessory belt routing section of this manual.
   
2. Rotate belt tensioner clockwise and slip drive belt over idler pulley on tensioner.
   

INSTALLATION

1. Using a vise, lightly compress the secondary chain tensioner piston until the piston step is flush with the tensioner body. Using a pin or suitable tool, release ratchet pawl by pulling pawl back against spring force through access hole on side of tensioner. While continuing to hold pawl back, Push ratchet device to approximately 2 mm from the tensioner body. Install Special Tool 8514 lock pin into hole on front of tensioner. Slowly open vise to transfer piston spring force to lock pin (Resetting Secondary Chain Tensioners).
2. Position primary chain tensioner over oil pump and insert bolts into lower two holes on tensioner bracket. Tighten bolts to 28 N·m (250 in. lbs.). CAUTION: Overtightening the tensioner arm torx® bolt can cause severe damage to the cylinder head. Tighten torx® bolt to specified torque only.
   
3. Install right side chain tensioner arm. Apply Mopar® Lock N, Seal to torx® bolt, tighten bolt to 17 N·m (150 in. lbs.). NOTE: The silver bolts retain the guides to the cylinder heads and the black bolts retain the guides to the engine block.
   
4. Install the left side chain guide. Tighten the bolts to 28 N·m (250 in. lbs.). CAUTION: Overtightening the tensioner arm torx® bolt can cause severe damage to the cylinder head. Tighten torx® bolt to specified torque only.
   
5. Install left side chain tensioner arm. Apply Mopar® Lock N, Seal to torx® bolt, tighten bolt to 17 N·m (150 in. lbs.).
6. Install the right side chain guide. Tighten the bolts to 28 N·m (250 in. lbs.).
7. Install both secondary chains onto the idler sprocket. Align two plated links on the secondary chains to be visible through the two lower openings on the idler sprocket (4 o'clock and 8 o'clock). Once the secondary timing chains are installed, position special tool 8515 to hold chains in place for installation (Installing Secondary Timing Chains on Idler Sprocket).
8. Align primary chain double plated links with the timing mark at 12 o'clock on the idler sprocket. Align the primary chain single plated link with the timing mark at 6 o'clock on the crankshaft sprocket (Timing Chain System).
9. Lubricate idler shaft and bushings with clean engine oil.
10. Install all chains, crankshaft sprocket, and idler sprocket as an assembly (Installing Idler Gear, Primary and Secondary Timing Chains). After guiding both secondary chains through the block and cylinder head openings, affix chains with a elastic strap or the equivalent, This will maintain tension on chains to aid in installation. NOTE: It will be necessary to slightly rotate camshafts for sprocket installation.
    
11. Align left camshaft sprocket “L” dot to plated link on chain.
12. Align right camshaft sprocket “R” dot to plated link on chain. CAUTION: Remove excess oil from the camshaft sprocket bolt. Failure to do so can result in over-torque of bolt resulting in bolt failure.
    
13. Remove Special Tool 8515, then attach both sprockets to camshafts. Remove excess oil from bolts, then Install sprocket bolts, but do not tighten at this time.
14. Verify that all plated links are aligned with the marks on all sprockets and the “V8” marks on camshaft sprockets are at the 12 o'clock position (Timing Chain System). CAUTION: Ensure the plate between the left secondary chain tensioner and block is correctly installed.
    
15. Install both secondary chain tensioners. Tighten bolts to 28 N·m (250 in. lbs.). NOTE: Left and right secondary chain tensioners are not common.
    
16. Before installing idler sprocket bolt, lubricate washer with oil, and tighten idler sprocket assembly retaining bolt to 34 N·m (25 ft. lbs.).
17. Remove all locking pins (3) from tensioners. CAUTION: After pulling locking pins out of each tensioner, DO NOT manually extend the tensioner(s) ratchet. Doing so will over tension the chains, resulting in noise and/or high timing chain loads.
    
18. Using Special Tool 6958, Spanner with Adaptor Pins 8346, tighten left (Tightening Left Side Camshaft Sprocket Bolt) and right (Tightening Right Side Camshaft Sprocket Bolt). camshaft sprocket bolts to 122 N·m (90 ft. lbs.).
19. Rotate engine two full revolutions. Verify timing marks are at the follow locations:
    • primary chain idler sprocket dot is at 12 o'clock (Timing Chain System)
    • primary chain crankshaft sprocket dot is at 6 o'clock (Timing Chain System)
    • secondary chain camshaft sprockets “V8” marks are at 12 o'clock (Timing Chain System)
20. Lubricate all three chains with engine oil.
21. After installing all chains, it is recommended that the idler gear end play be checked (Measuring Idler Gear End Play). The end play must be within 0.10–0.25 mm (0.004–0.010 in.). If not within specification, the idler gear must be replaced.
22. Install timing chain cover (Refer to 9 - ENGINE/VALVE TIMING/TIMING BELT / CHAIN COVER(S) - INSTALLATION) and crankshaft damper (Refer to 9 - ENGINE/ENGINE BLOCK/VIBRATION DAMPER - INSTALLATION).
23. Install cylinder head covers (Refer to 9 - ENGINE/CYLINDER HEAD/CYLINDER HEAD COVER(S) - INSTALLATION). NOTE: Before installing threaded plug in right cylinder head, the plug must be coated with sealant to prevent leaks.
    
24. Coat the large threaded access plug with Mopar® Thread Sealant with Teflon, then install into the right cylinder head and tighten to 81 N·m (60 ft. lbs.) (Cylinder Head Access Plug Location).
25. Install the oil fill housing.
26. Install access plug in left cylinder head (Cylinder Head Access Plug Location).
27. Install power steering pump (Refer to 19 - STEERING/PUMP - INSTALLATION).
28. Install radiator fan shroud.
29. Fill cooling system (Refer to 7 - COOLING - STANDARD PROCEDURE).
30. Connect negative cable to battery.

1.Your engine has an internal timing chain, not a belt.
Therefore I'm going to assume that you mean the serpentine drive belt.
Common causes for belt to fail is either a mis-aligned or damaged pulley, improper belt tension, or bad tensioner spring (if equipped with spring loaded tensioner) You mentioned a loose pulley but didn't say which one! That's what I'd look at first! Also, make sure that all pulleys have no "wobble" indicating a bad pulley bearing Most common: water pump or idler pulley.